In a field of intellectual production, not labor but knowledge is main production means. However, in recent years, the knowledge has been rapidly obsoleted with the evolution of a constantly advancing technology, and intellectual workers themselves cannot maintain their expertise. The intellectual workers of today are required to always improve a capability and knowledge for maintaining their expertise. Also, the intellectual workers of today are required to provide a consensus formation skill for actualizing diverse values underlying a stakeholder through discussion, and rapidly making a decision of an organization.
In order that the organization maintains a competing power in the intellectual production, it is essential to objectively and precisely evaluate a decision making process of the intellectual workers configuring their organization, and always change actions of the intellectual workers within the organization.
Instead of the organization evaluation by a conventional qualitative evaluation depending on individual skills, a technology has been developed in which a communication within the organization is visualized by the aid of a sensor technology, and a quality of the intellectual production process is objectively evaluated.
Hardware, a system, and an analysis technique of the sensor terminal have been disclosed in which facing of persons is recorded with the use of an infrared transmitter provided in each of terminals dangled from persons' necks, and information on one person who faces another person, and information acquired by an acceleration sensor are synthesized for visualizing the communication within the organization (for example, refer to Nonpatent Literature 1).
In a system disclosed in Nonpatent Literature 1, the sensor terminal includes a pair of infrared transceivers for detecting a face-to-face communication. Because infrared rays are high in directivity as compared with radio, the infrared transceivers do not undergo reaction only when the respective wearers stay in proximity to each other sideways or backward, and are excellent in accurately detecting that the respective wearers face each other.
In most cases, the infrared rays are used in the system of this type, but the optical communication may use a light different in wavelength from the infrared rays (for example, a visible light and an ultraviolet light) if linearity and directivity are generally high.
Within the organization, there are not only a case in which two persons having the similar body types face each other, but also a case in which wearing positions of the sensor terminals of facing persons are different from each other due to a difference in the body type, a case in which one of the facing persons sits, and a case in which the facing persons are displaced from front face positions to face each other. A sensor terminal has been disclosed in which a plurality of infrared transceivers is arranged with an alteration of angles in order to detect the above-mentioned facing while limiting a communication range of the infrared communication to a desired range (for example, refer to Patent Literature 1).
The sensor terminal disclosed in Patent Literature 1 includes diverse sensors in addition to the infrared transceiver, in order to more precisely acquire states of people configuring the organization. Specifically, the diverse sensors include an acceleration sensor for detecting an orientation and motion of the sensor terminal, a microphone for acquiring speech and environmental sound, and a temperature sensor and an illumination sensor for acquiring the environment. Those sensors are easily affected by a variation in supply voltage and a radiation noise because the sensors deal with a minute analog signal. In particular, during the operation of the infrared transmitter, a large current of hundreds of mA to several A instantaneously flows into a circuit board of the sensor terminal at the timing of emitting the infrared rays. Therefore, special consideration needs to be given to a power supply design and a circuit arrangement for the purpose of preventing the diverse sensors from being affected by the variation in the supply voltage and the radiation noise from circuit lines.